We propose a modification to the Non-linear Asymptotic Coupling Theory (NACT), a normal mode coupling method used for synthesizing seismograms and computing sensitivity kernels in 3D Earth. The modification is aimed to meet the computational challenges for NACT when approaching higher frequencies, which is required for obtaining finer scale images of the Earth's upper mantle. The new scheme is ...

Seismic velocity discontinuities are commonly found within the upper 100 km of the mantle lithosphere, with great variability in their depth, lateral extent, and the polarity of velocity jump. Among the more commonly observed is the ‘80 km’ or Hales discontinuity, identified in a variety of tectonic environments, and sometimes associated with seismic anisotropy. Teleseismic receiver functions f...

New derivations of Young–Laplace’s and Young’s equations for a liquid drop deposited on a smooth solid substrate are presented, based on an integral form of equilibrium conditions applied to appropriately selected finite portions of the drop. A simple proof for the gravity independence of the contact angle is constructed and compared with a commonly utilized but more involved proof based on the...

We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, wh...

It is well established that the free-space Green's function can be recovered from the two-point cross-correlation function of a random noise field if the noise is white and isotropic. Ambient noise in the ocean rarely satisfies either of these conditions. However, a non-uniform spectrum could be pre-whitened by the application of a suitable filter but anisotropy cannot be so readily eliminated....

This paper is partly born of an increasing sense of uncertainty about how to do syntax. Time was, we linguists had at our disposal a generally accepted arsenal of analytic devices to deal with a familiar range of constructions and phenomena. However, as the phenomena under study began to proliferate, so did the analyses. The increasingly baroque GB architecture began to collapse under the weigh...

The 41 0-kilometer seismic discontinuity is generally considered to be caused by a phase transformation of the main constituent of the upper mantle, olivine, ot-(Mg,Fe)2SiO4, to P-(Mg,Fe)2SiO4. Recent data show that H20 dissolves in olivine and other nominally anhydrous mantle minerals and that the partitioning of H20 between olivine and P-(Mg,Fe)2Si04 is about 1:10. Such behavior strongly affe...

Investigation of vertical vibrations of a railway turnout is important in designing track components under moving loads of trains. In this paper, the turnout is simulated by a linear finite element model with modal damping. A section of the turnout has a length of 36 sleeper spans surrounding the crossing. Rails and sleepers are modeled with uniform Rayleigh- Timoshenko beam elements. The rail...

[1] Receiver functions recorded by the 54‐station 920 km long Program for Array Seismic Studies of the Continental Lithosphere–Incorporated Research Institutions for Seismology Colorado Plateau/Rio Grande Rift Seismic Transect Experiment (LA RISTRA) line array display a pervasive negative polarity P to S conversion (Pds) arrival preceding the positive polarity 410 km discontinuity arrival. Thes...